1. Field of the Invention
The present invention provides methods of consolidating subterranean zones and hardenable resin compositions therefor.
2. Description of the Prior Art
Hydrocarbon producing wells are often completed in unconsolidated formations containing loose and incompetent particulate solids which migrate with hydrocarbons or hydrocarbons and water produced by the wells. The presence of the particulate solids in the produced fluids is highly undesirable in that the solid particles abrade tublar goods, pumping equipment, valves and other producing equipment and reduce the fluid production capabilities of the producing zones in the wells. Incompetent subterranean formations include those which contain loose particulate solids that are readily entrained by produced fluids and those wherein the particulate solids making up the formations are bonded together with insufficient strength to withstand the forces produced by the production of fluids from the formations. A technique which is often used for minimizing particulate solid production from unconsolidated formations has been to produce fluids from the formations at low flow rates whereby the near well stabilities of particulate solid bridges and the like in the formations are preserved. However, the collapse of such particulate solid bridges often occurs as a result of unintentional high production rates and/or pressure cycling. Pressure cycling occurs from frequent shut-ins and start-ups of a well. The frequency of the pressure cycling is very critical to the longevity of the near well formation, especially during the depletion stage of the well when the pore pressure of the formation has already been significantly reduced.
Heretofore, unconsolidated formations have been treated by injecting hardenable resin compositions into the formation and then allowing the resin compositions to harden whereby the unconsolidated formations are consolidated. While such heretofore utilized consolidating techniques have been used successfully, in high temperature subterranean zones, i.e., subterranean zones having temperatures above about 200° F., the hardenable resins have been broken down by chemical attack and/or thermal degradation thereby again allowing particulate solids to migrate with produced fluids. Also, to ensure that particulate solids are not produced, costly gravel packs, sand screens and the like have been installed in subterranean producing formations. However, because gravel packs and sand screens filter out particulate solids from the produced fluids, the presence of the filtered particulate solids adds to the flow resistance thereby producing additional pressure draw down which causes portions of the unconsolidated formations to break down.
Thus, there are needs for improved methods and hardenable resin compositions for consolidating unconsolidated subterranean zones whereby particulate solids do not migrate with produced fluids.